skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nanostructure transition: From solid solution Ti(N,C) to nanocomposite nc-Ti(N,C)/a-(C,CN{sub x})

Abstract

A nanostructure transition from solid solution (SS) Ti(N,C) to two-phase nanocrystalline (nc)-Ti(N,C)/amorphous (a)-(C,CN{sub x}) thin films was investigated using a combination of high-resolution transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. The finding of the authors is that such a nanostructure transition was strongly controlled by the relative atomic ratio x[x{identical_to}(C+N)/Ti]. The results indicated that SS Ti(N,C) and uncompleted and completed segregated two-phase nanocomposite nc-Ti(N,C)/a-(C,CN{sub x}) were successively formed at x{<=}1.0, 1.0<x<1.2, and x{>=}1.2, respectively. Increase of the x values not only decreased the grain size and promoted the formation of more [200]-oriented nanocrystallites but also produced more disorders and defects in thin films. A maximum hardness was achieved for a SS Ti(N,C) structure at x=1.0. The corresponding nanostructure transition mechanism is also discussed.

Authors:
;  [1]
  1. Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, Kowloon, Hong Kong (China)
Publication Date:
OSTI Identifier:
20971943
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 22; Other Information: DOI: 10.1063/1.2745261; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AMORPHOUS STATE; CARBON; CARBON COMPOUNDS; COMPOSITE MATERIALS; CRYSTALS; GRAIN SIZE; HARDNESS; NANOSTRUCTURES; PHASE TRANSFORMATIONS; SEGREGATION; SOLID SOLUTIONS; THIN FILMS; TITANIUM COMPOUNDS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Lu, Y. H., and Shen, Y. G.. Nanostructure transition: From solid solution Ti(N,C) to nanocomposite nc-Ti(N,C)/a-(C,CN{sub x}). United States: N. p., 2007. Web. doi:10.1063/1.2745261.
Lu, Y. H., & Shen, Y. G.. Nanostructure transition: From solid solution Ti(N,C) to nanocomposite nc-Ti(N,C)/a-(C,CN{sub x}). United States. doi:10.1063/1.2745261.
Lu, Y. H., and Shen, Y. G.. Mon . "Nanostructure transition: From solid solution Ti(N,C) to nanocomposite nc-Ti(N,C)/a-(C,CN{sub x})". United States. doi:10.1063/1.2745261.
@article{osti_20971943,
title = {Nanostructure transition: From solid solution Ti(N,C) to nanocomposite nc-Ti(N,C)/a-(C,CN{sub x})},
author = {Lu, Y. H. and Shen, Y. G.},
abstractNote = {A nanostructure transition from solid solution (SS) Ti(N,C) to two-phase nanocrystalline (nc)-Ti(N,C)/amorphous (a)-(C,CN{sub x}) thin films was investigated using a combination of high-resolution transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. The finding of the authors is that such a nanostructure transition was strongly controlled by the relative atomic ratio x[x{identical_to}(C+N)/Ti]. The results indicated that SS Ti(N,C) and uncompleted and completed segregated two-phase nanocomposite nc-Ti(N,C)/a-(C,CN{sub x}) were successively formed at x{<=}1.0, 1.0<x<1.2, and x{>=}1.2, respectively. Increase of the x values not only decreased the grain size and promoted the formation of more [200]-oriented nanocrystallites but also produced more disorders and defects in thin films. A maximum hardness was achieved for a SS Ti(N,C) structure at x=1.0. The corresponding nanostructure transition mechanism is also discussed.},
doi = {10.1063/1.2745261},
journal = {Applied Physics Letters},
number = 22,
volume = 90,
place = {United States},
year = {Mon May 28 00:00:00 EDT 2007},
month = {Mon May 28 00:00:00 EDT 2007}
}
  • Reactions between Ru(C{sub 2}Me)(PPh{sub 3}){sub 2}({eta}-C{sub 5}H{sub 5}) or Ru(C{sub 2}Ph)(L){sub 2}({eta}-C{sub 5}H{sub 5}) (L{sub 2} = (PPh{sub 3}){sub 2}, dppe, (CO)(PPh{sub 3})) and (CF{sub 3}){sub 2}C=C(CN){sub 2} gave the corresponding {sigma}-cyclobutenyl complexes, of which Ru(C=CPhC(CF{sub 3}){sub 2}C(CN){sub 2})(CO)(PPh{sub 3})({eta}-C{sub 5}H{sub 5}) (1g) was fully characterized by X-ray crystallography. Thermal isomerization of the dppe and (CO)(PPh{sub 3}) complexes to the {sigma}-buta-1,3-dien-2-yl derivatives occurred; under CO, two isomers of Ru(C(=C(CN){sub 2})CMe=C(CF{sub 3}){sub 2})(CO)(PPh{sub 3})({eta}-C{sub 5}H{sub 5}) were formed. The X-ray structures of one of these (2h), and the phenyl analogue (2g), were determined. The allyls Ru({eta}{sup 3}-C(CF{sub 3}){sub 2}CXC=C(CN){sub 2})(PPh{sub 3})({eta}-C{submore » 5}H{sub 5}) (X = Me (3d), Ph (3g)) were obtained thermally or photochemically; the structure of 3g was also determined, thus completing the series {sigma}-cyclobutenyl, {sigma}-butadienyl, {eta}{sup 3}-allyl derived from the same metal/ligand combinations. Crystal data for 1g: orthorhombic, space group P2{sub 1}2{sub 1}2{sub 1}, a = 10.409 (2) {angstrom}, b = 16.227 (3) {angstrom}, c = 20.000 (3) {angstrom}, Z = 4; 2,851 data were refined to R = 0.040, R{sub w} = 0.041. Crystal data for 2g; monoclinic, space group P2{sub 1}/n, a = 14.942 (1) {angstrom}, b = 13.413 (2) {angstrom}, c = 16.928 (6) {angstrom}, {beta} = 97.02 (1){degree}, Z = 4; 3,659 data were refined to R = 0.045, R{sub w} = 0.059. Crystal data for 2h: monoclinic, space group C2/c, a = 22.237 (4) {angstrom}, b = 18.648 (5) {angstrom}, c = 17.731 (3) {angstrom}, {beta} = 124.93 (2){degree}, Z = 8; 3,076 data were refined to R = 0.039, R{sub w} = 0.042.« less
  • The grain growth in two-phase nanocomposite Ti-C{sub x}-N{sub y} thin films grown by reactive close-field unbalanced magnetron sputtering in an Ar-N{sub 2} gas mixture with microstructures comprising of nanocrystalline (nc-) Ti(N,C) phase surrounded by amorphous (a-) (C,CN{sub x}) phase was investigated by a combination of high-resolution transmission electron microscopy (HRTEM) and Monte Carlo (MC) simulations. The HRTEM results revealed that amorphous-free solid solution Ti(C,N) thin films exhibited polycrystallites with different sizes, orientations and irregular shapes. The grain size varied in the range between several nanometers and several decade nanometers. Further increase of C content (up to {approx}19 at.% C) mademore » the amorphous phase wet nanocrystallites, which strongly hindered the growth of nanocrystallites. As a result, more regular Ti(C,N) nanocrystallites with an average size of {approx}5 nm were found to be separated by {approx}0.5-nm amorphous phases. When C content was further increased (up to {approx}48 at.% in this study), thicker amorphous matrices were produced and followed by the formation of smaller sized grains with lognormal distribution. Our MC analysis indicated that with increasing amorphous volume fraction (i.e. increasing C content), the transformation from nc/nc grain boundary (GB)-curvature-driven growth to a/nc GB-curvature-driven growth is directly responsible for the observed grain growth from great inhomogeneity to homogeneity process.« less
  • Replacement of MeCN in Ru(C{double bond}CPhC(CF{sub 3}){sub 2}C(CN){sub 2})(NCMe)(PPh{sub 3})({eta}-C{sub 5}H{sub 5}), readily obtained from the bis-PPh{sub 3} complex in MeCN, by a series of organonitrile ligands (CH{sub 2}{double bond}CHCN,trans-CH(CH){double bond}CH(CN), C(CN){sub 2}{double bond}C(CF{sub 3}){sub 2} (dcfe), C{sub 2}(CN){sub 4}, o-C{sub 6}H{sub 4}(CN){sub 2}, p-C{sub 6}H{sub 4}(CN){sub 2}, o-C{sub 6}F{sub 4}(CN){sub 2}, p-C{sub 6}F{sub 4}(CN){sub 2}, C{sub 6}H{sub 2}(CN){sub 4}) has given highly colored complexes containing one or two Ru(C{double bond}CPhC(CF{sub 3}){sub 2}C(CN){sub 2})(PPh{sub 3})({eta}-C{sub 5}H{sub 5}) moieties. The binuclear complexes are bridged by the di- or tetranitriles; isomers were found for the fumaronitrile, dcfe, and C{sub 2}(CN){sub 4} derivaties.more » The deep blue {mu}-dcfe complexes are readily oxidized to green paramagnetic species that appear to contain an epoxy radical ligand. The complexes were characterized by spectroscopic and electrochemical studies and, in the case of the title complexes, by single-crystal X-ray diffraction studies. The structures were refined by a full-matrix (blocked-matrix for 2a) least-squares procedure to final R = 0.059 and R{sub w} = 0.064 for 3,883 reflections with I {ge} 2.5{sigma}(I) for 4 and R = 0.045 and R{sub w} = 0.045 for 1,708 reflections for 2a.« less
  • Ru{sub 2}(O{sub 2}C(CH{sub 2}){sub 6}CH{sub 3}){sub 4} (1a) is soluble in both coordinating (THF, CH{sub 3}OH, CH{sub 3}CN) and noncoordinating solvents (benzene, toluene, cyclohexane, CH{sub 2}Cl{sub 2}), allowing its solution properties to be investigated by {sup 1}H and {sup 13}C NMR spectroscopy, UV/visible spectroscopy, resonance Raman spectroscopy, and cyclic voltammetry. In noncoordinating solvents, 1a exists as an oligomer, presumably by way of axial intermolecular -(--[Ru{sub 2}]--O--){sub n}-interactions. {sup 1}H NMR studies of 1a and [Ru{sub 2}(O{sub 2}C(CH{sub 2}){sub 6}CH{sub 3}){sub 4}]{sup +}[X]{sup {minus}}([1a]{sup +}[X]{sup {minus}}), where X = Cl, BF{sub 4}, or O{sub 2}C(CH{sub 2}){sub 6}CH{sub 3}, indicate that bothmore » dipolar and contact mechanisms contribute to the paramagnetic shifts of the protons. Resonances for axial and equatorial ligands are shifted upfield and downfield, respectively, by a dipolar mechanism. Aromatic ligands in the axial sites, e.g. pyridine and pyrazine, experience an enhanced upfield shift by direct {pi}-delocalization. Comparison of the {sup 1}H NMR signals for M{sub 2}(O{sub 2}CR){sub 4} compounds where M = Ru and O{sub 2}CR = benzoate, toluate, butyrate, crotonate, and dimethylacrylate with those where M = Mo indicates that the equatorial carboxylate ligands in the diruthenium species also experience {pi}-contact shifts. Variable-temperature studies and calculated estimates of dipolar shifts indicate a significant zero-field splitting contribution to the dipolar shift. The arrangements of the toluate rings in Ru{sub 2}(O{sub 2}C -p-tolyl){sub 4}-(THF){sub 2}, Ru{sub 2}(O{sub 2}C-p-tolyl){sub 4}(CH{sub 3}CN){sub 2}, and [Ru{sub 2}(O{sub 2}C-p-tolyl){sub 4}(THF){sub 2}]{sup +}[BF{sub 4}]{sup {minus}} deviate by 15(1), 2.3(2), and 7.3{degrees}, respectively, form alignment with the Ru-Ru axis.« less
  • Ti-C{sub x}-N{sub y} thin films with different amounts of C incorporated into TiN{sub 0.87} were deposited on Si(100) substrates at 500 deg. C by reactive unbalanced dc magnetron sputtering. Their phase configuration, nanostructure, and mechanical behavior were investigated by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and microindentation measurements. The results indicated that the atomic ratio of (C+N)/Ti played a crucial role in phase configuration, nanostructure evolution, and mechanical behavior. When the ratio was less than one, a nanocrystalline (nc-) Ti(C,N) solid solution was formed by dissolution of C into the TiN lattice. Both microhardnessmore » and residual compressive stress values increased with an increase of C content. When the C reached saturation, precipitation of small amounts of sp{sup 2} amorphous (a-) phase appeared with more C incorporation. Further increase of C content (up to {approx}19 at. % C) made the amorphous phase fully wet nanocrystallites, which resulted in the formation of nanocomposite thin films of {approx}5 nm nc-Ti(C,N) nanocrystallites separated by an {approx}0.5 nm amorphous phase comprised mainly of sp{sup 2} disordered C, graphite, and minor CN{sub x}. Thicker amorphous matrices and smaller sized grains followed when C content was further increased. The formation of nanocomposite structure greatly decreased both hardness and residual stress values of thin films. A hardness maximum was believed to be obtained at nc-Ti(C,N) solid solution containing the maximum C amount. Enhancement of the hardness value was attributed to solid solution effect and high residual stress value.« less